Ledipasvir (LDV) (The structure is shown in formula I) is a hepatitis C drug developed by Gilead, and FDA has granted a breakthrough therapy designation of LDV/SOF (Sofosbuvir) fixed dose combination that is expected to cure genotype 1 HCV patients in as short as 8 weeks without injection of interferon or combination with Ribavirin.

Crystal form is a term used to describe the crystalline state of a compound and encompasses polymorphs, solvates, salts, eutectics and the like. The crystal form has a profound effect on the physical and chemical properties of the compound such as stability, solubility, powder properties and the like. At the same time, the crystallization process is also an important means to remove impurities and thereby improve product quality in the pharmaceutical process.
Due to its molecular structure, Ledipasvir has poorer crystallinity and photostability. At present, Gilead's patent US20130324496A1 has claimed Ledipasvir diacetone solvate and monoacetone solvate. These two crystal forms show a better purification effect by crystallization, of which the photostability is better than that of amorphous but the degradation is still as high as 6.3% after 1.2 million lux·hours of illumination, and which can't meet the practical application demand well.
Therefore, there is an urgent need in the art to develop a new crystal form of Ledipasvir to further improve its crystallinity and stability, thereby to promote its production and application.